CB Coxial cable

I don't know what length my CB coax is, but it's not 18' and I get a SWR of about 1.5 More than adequate for trail use. The "perfect location" for a CB antennae is at the highest point, dead center of your vehicle. From that point your signal radiates equally in all directions. That locations doesn't really work for a Jeep so I put mine over the spare tire.

 

Damn Panzer, you gotta nice rig!!:drool:

 

yes he does....
but nobody has ever seen it up close
cuz he never shows up anywhere


I have my extra coax on top of the under seat tank (on topic)

 

The shield will isolate the center conductor from EMF and capacitive coupling in theory. However, braided shielding does not provide 100% isolation - look at the specs for the cable. IIRC you get something like 50-80% isolation with a braided shield, and somewhat better with foil or foil plus braid.

If you really want to explore this topic, I'd recommend this book

http://www.amazon.com/Noise-Reducti...=sr_1_1?ie=UTF8&s=books&qid=1216223546&sr=1-1

I own it and have read it, but I'd have to refer to it to for any specific points. If you build gadgets to use in the MRI room (I have) you must pay attention to rf isolation and environmental noise.

Not picking on Howard specificallaly, but I'm saying you can't make a blanket statement like "cable routing doesn't matter" - it does. The type of cable matters. The length of cable matters. The orientation of the antenna matters - some are designed to work above a ground plane (like mounted on a cowl) and some are meant for free air mounting. There is a lot to antenna design. You need to tune and match the antenna with it mounted in place.

I'd say buy a quality antenna and mount it according to the instructions. Use the best quality cable and connectors you can buy, and route the shortest cable with the most free air around it as possible. Pay close attention to the quality of your connector mountings, grounds, and seal up the CB box with copper tape. Solder the copper tape to the CB case as many places as you can. Give your CB clean power - Corcom style filters work well, and shield the power leads between the filter and the CB case. Not sure how much of this is needed, but I think all of it will help.

 

Lots of very good information in this thread!

Thanks Guys !!!

 

Ott's the man when it comes to noise reduction, I took the class over 15 years ago. His book resides on the shelf above my desk at work.